1. Field of the Invention
The present invention relates generally to systems and methods for monitoring moisture of grain as it is being harvested by a combine thresher and more particularly to such systems which are mounted externally on combine threshers.
2. Description of the Prior Art
A combine thresher, is used by farmers to harvest grain. The combine cuts the grain plants growing in a field and separates the grain from the rest of the plant. A combine draws the plants into the combine using a thresher mechanism. Grates separate the grain from the rest of the plant, often called the chaff, in some instances by having a fan blow away the lighter chaff from the relatively heavy grain. The separated grain, often called clean grain, is collected at the bottom of the thresher on the grain floor and is moved by an auger located there to an elevator which raises the grain to a grain accumulator or bin where the grain is held for off loading to transport trucks. A bin auger feeds the grain bin from the grain elevator top discharge.
The clean grain collected in the bin of the combine is eventually transferred to trucks and taken to drying bins, to farm storage, or directly to grain elevators. Where the grain is taken often depends on the moisture content of the grain. Proper grain requires to be below a certain moisture content. Wet harvested grain must be first dried in a drying bin to lower the moisture content before it is stored. Thus there are obvious advantages to keeping track of the moisture of the grain as it is being harvested by the combine.
Also, some farmers use a grid system which may be stored in a computer data base to plot out each of their fields on paper. The grid system is used to keep track of yield due to different weather factors and grain conditions for each section of the grid, where each section corresponds to a certain area of the actual field. Because moisture content is such an important factor in grain production, it is very advantageous for the farmer to monitor and keep track of the moisture content of grain being harvested from any grid section of the field to provide corrections as needed thereto for uniform production.
Combine threshers are known to include in-situ moisture analyzers which are temperature compensated for measuring the moisture content and temperature of the harvested grain. An example of such is disclosed in U.S. Pat. No. 5,106,339. Such in-situ moisture monitoring systems include a sensor assembly positioned in the clean grain auger of the harvester for sensing the moisture content of grain moving through the auger. The operation of the moisture monitoring system is controlled by a microprocessor which controls a display connected to the moisture monitoring system for displaying the moisture of the grain flowing through the clean grain auger. Additionally, the microprocessor samples the moisture readings and averages them over a selectable period of time.
Mounting the sensor internally to the auger creates a number of problems which include:
the output readings are subject to errors due to variations in the density of the grain flowing past the sensor, PA1 the output readings are subject to errors due to the gradual buildup of deposits on the sensor, PA1 the sensor is difficult to access for cleaning and repair, PA1 it is expensive and time consuming to install the sensor on existing combines.
Thus, there is a need for a sensor with improved performance that can be easily and inexpensively retro fitted to existing combines.